Ethylene glycol toxicity

From IDWiki

Summary

  • AGMA with osmolar gap, hypocalcemia, AKI, hematuria, and obstruction
  • Osmolar gap becomes anion gap as metabolism progresses

Pathophysiology

graph TD
eg["Ethylene glycol"] --> |Alcohol dehydrogenase|glycerald
glycerald["Glyceraldehyde"] --> |Aldehyde dehydrogenase|glycolate
glycolate["Glycolate"] --> glycox
glycox["Glycoxylate"] --> |Thiamine & pyridoxine|metabs["Less toxic metabolites"]
glycox --> oxalate
oxalate["Oxalate"] --> |Calcium|caox
caox["Calcium oxalate"]
  • Glycolate causes renal tubular damage and oxalate crystal cause urinary obstruction
  • Hypocalcemia secondary to calcium oxalate formation

Sources

  • Antifreeze
  • Windshield fluid
  • Cleaners
  • Fuels
  • Moonshine

Clinical Manifestations

  • Decreased LOC
  • Hematuria with flank pain and oliguria
  • Hypocalcemia
    • Cranial nerve palsies
  • Coma, seizures, tachypnea, and hypotension in late stage

Investigations

  • Anion gap metabolic acidosis with osmolar gap
    • As metabolism progresses the initial osmolar gap is replaced by an anion gap
  • Order acetaminophen and salicylate levels as well
  • Lactate can be elevated, either because of lactate or because of false-positive from the ethylene glycol
  • Monitor renal function, including electrolytes, extended lytes (calcium), and creatinine
  • Urine microscopy for calcium oxalate crystals, which show up as needle-shaped crystals
  • Monitor ECG for QTc prolongation from hypocalcemia

Management

  • ABCs
  • NG aspiration if within 60 minutes
  • Sodium bicarb if pH <7.3, with infusion to target pH ≥ 7.35
  • Thiamine and pyridoxine to shunt glycoxylate metabolism toward less harmful metabolites
  • Fomepizole or ethanol, which competitively inhibit alcohol dehydrogenase
    • Serum ethylene glycol >3.2 mmol/L, or
    • Documented toxic ingestion and an osmolar gap > 10, or
    • Suspected toxic ingestion and 2 of:
      • pH < 7.3
      • Bicarb < 20
      • Gap (which one?) > 10
      • Urinary oxalate crystals
  • Hemodialysis if ongoing acidosis and evidence of end-organ damage